I have a Sta-Rite Irrigation pump(DS3HF-01) that was leaking because the seal and diffuser ring were bad. After fixing the leak, the pump keeps tripping out the circuit breaker. I change the circuit breaker, the pump start relay, the centrifugal motor switch, and the capacitor. It still keep tripping out the circuit whenever I turn on the sprinkler system. It was working fine before I decided to fix the leak. What else could be wrong? Please help!

If you tightened the seal too much or improperly installed the seal and diffuser ring, you could be binding the pump shaft. Are you sure it is the right diffuser? Same number of vanes? Overload on start up.

Yes, it's the right diffuser ring.