When I go to turn on my shower, water keeps coming from the tub spicket. I have a three knob shower system. I took the stem out and repalced the gasket and 0-ring(both totally gone and that did not fix the problem. It's not an urgent issue,just annoying(and wasteful). Any advice would be greatly appreciated.

The knob in the center is your diverter and that is the only one you should work on for this fix. Is this the one you worked on? A brand or model would help as would a picture. This seal has failed and if you replaced it there may be a wrong part or not plumbers grease used.