How to copy and paste data into middle of other cell without overwriting?

I have 2 columns and want to copy the one rows data into a certain spot in other cell.

For example row 1 has
8766
7446
6633

Row 2 has a link to images I need so
Www.example.com/images/item(need to paste to here).jpg

I need to copy and paste the row of numbers to item(blank).jpg.

Not sure if that makes sense. I have 29,000 images and don't want to type each link manually

That is a simple formula I think.
in A3 type:

=left(A2,len(A2)-4) & A1 & ".jpg"

fill to the right.