ggplot: label points with plotmath expressions

I tried several methods to add superscript "+" with other strings as point labels in plot in R but it failed.

for example:

I know how to add single superscript "+" below:
plot(1:10,xlab = expression("ABC"^"+"))

It really work when I just want to add superscript "+" on x axis through xlab.

But I want to add multiple points with superscript labels, such as expression("EFG"^"+"), expression("HIJ"^"+") and so on.

When I put it into ggplot2, error information appeared:

Don't know how to automatically pick scale for object of type <expression>. Defaulting to continuous.
Error in `geom_text_repel()`:
! Problem while computing aesthetics.
i Error occurred in the 2nd layer.
Caused by error in `compute_aesthetics()`:
! Aesthetics are not valid data columns.
x The following aesthetics are invalid:
x `label = hh`
i Did you mistype the name of a data column or forget to add `after_stat()`?
Run `rlang::last_trace()` to see where the error occurred.
> 

Here is my reproducible example code:

library(ggrepel)
library(ggplot2)
data <- data.frame(x = 1:3,                 # Create example data
                   y = 1:3,
                   label = LETTERS[1:3])
data  

hh<-c(expression("ABC"^"+"),
      expression("EFG"^"+"),
      expression("HJK"^"+"))
plot(data$x,                                # Draw plot
     data$y,
     xlim = c(1, 4))
text(data$x,                                # Add labels
     data$y,
     labels = hh,
     pos = 4)

ggplot(data = data,aes(x=x,y=y))+
  geom_point()+
  geom_text_repel(aes(label = hh))

I hope somebody can give me some advice. Thanks in advance.

1. hh doesn't need to be expressions, it just needs to contain the text of the expression. We add geom_text_repel(..., parse=TRUE) so that it treats the character strings as expressions correctly.
2. I think the better way to define that expression is as 'ABC^"+"' or "ABC^'+'" so that the + is not interpreted as the math operator.
3. Technique, I prefer to have the labels as part of the frame, so I'll add it to data, overriding your label. (But this is certainly not required, it's just "cleaner", in my opinion.)

data <- data.frame(x = 1:3,                 # Create example data
                   y = 1:3,
                   label = c("ABC^'+'", "EFG^'+'", "HJK^'+'"))
set.seed(42) # since ggrepel is stochastic, not required in production
ggplot(data = data,aes(x = x, y = y)) +
  geom_point() +
  geom_text_repel(aes(label = label), parse = TRUE)

(I added set.seed(42) purely so that you can get exactly this image, since the repel action is random. I recommend not using set.seed unless you find one specific seed which lays out the labels in a way you prefer. Without setting the seed, you will get a slightly-different plot each time you call it.)

I prefer r2evans' answer, but here's another way using annotate:

set.seed(1)
ggplot(data = data,aes(x=x,y=y))+
    geom_point()+
    annotate(geom = "text_repel", x = data$x, y = data$y, label = hh)