Use wc on all subdirectories to count the sum of lines

Perhaps you are looking for exec option of find.

find . -type f -exec wc -l {} \; | awk '{total += $1} END {print total}'

You probably want this:

find . -type f -print0 | wc -l --files0-from=-

If you only want the total number of lines, you could use

find . -type f -exec cat {} + | wc -l