You get lapping compound from auto parts, with key out, smear on shaft, install wheel, with light pressure spin wheel back/forth or round/round a bit. Wipe shaft, inside of wheel. if both have an even "look" you're done. If not, repeat until you do. Clean it pussy clean before final assembly. Lapping will get you a perfect fit between the two.
If I knew why I can't copy/paste here, I would do a LMGTFY, haha.
Google might get you a better idea.