There is a bump on my wrist that is hard and hurts. It isn't on my other wrist either. Would you know what it is?

Ganglion cyst? It is probably a ganglion cyst. A ganglion cyst, also known as ganglia, is a fluid-filled mass that can occur at any joint, but it most commonly found on the thumb and palm side of the wrist.
Possible cyst . To give you a final answer it would be good to take a look at it but one common occurrence that presents as lump in the wrist is a ganglion cyst which is a protuberance that grows from the tissues that cover your wrist bones. This is the possibility in your case. Anyway, get checked and make sure you get the appropriate diagnosis.