Where would I purchase a diverter stem, ours still leaks water through the handle when it is pulled out, I don't know if the seal is bad. But do I need to replace the diverter? And where can I purchase one?

Is the diverter on the valve or on the tub spout?

The diverter is on the valve

I think I need to replace the stem, would you know where to purchase it?

Does it have a nut around it that you can tighten? To replace you need to know brand or remove and take to plumbing supply, maybe they can identify.

Where would I purchase a diverter stem, ours still leaks water through the handle when it is pulled out, I don't know if the seal is bad. But do I need to replace the diverter? And where can I purchase one?
As Harold said, Take the old stem into a plumbing shop and match it up exactly.
Good luck. Tom

You can replace the washers and it could also be the seat behind the diverter stem. If they still make and it is price pfister, they will send you replacements if not too old of a house. You can send a photo. Plumbing supply is a good start & seat if that does not work.

I am having a problem because I can not find an exact replacement. I did once and pretty easy to take out & probably already an answer on here how to take it out.