How to Insert a character between existing characters in a text string?

How do I add a "-" in two different character positions within a text string?

For example, the current text string is WF121202 and I need to change it to WF121-2-02 for numerous rows of data.

If all of the cells follow the same length/structure, the following macro will work without the need for a helper column. (Note, the macro is set to apply to any selected cells)

Sub AddStuffAndStuff()
    Dim R As Range
    Dim arr(1 To 3) As String
    
    Set R = Selection
    For Each itm In R
        arr(1) = Left(itm, 5)
        arr(2) = Mid(itm, 6, 1)
        arr(3) = Right(itm, 2)
        
        itm.Value = arr(1) & "-" & arr(2) & "-" & arr(3)
    Next itm
    
End Sub

strOld = "WF121202"

strNew = Left(strOld, 5) & "-" & Mid(strOld, 6, 1) & "-" & Right(strOld, 2)

Great, it works!! Thanks a bunch!!! Yhis has saved me a lot of time!

Regards,
forti2ude95