The coupling itself is replaceable, p/n is 3278-0000. It is widely available, in the US for about 70.00.
If you're fairly proficient with tools, you may be able to replace the coupling without totally disassembling the pump. If the pump is working fine already there is no absolute need to replace any bearings or seals or anything else. I guess the logic is, 'since its off rebuild
it'. I prefer to fix things that need fixing.
Guess it's kinda like closing the barn door after the horses have escaped, but be careful reinstalling the pump when you get it fixed...