If it was allowed to run dry for a while that will burn out the motor.
Inspect the impeller, magnet, shaft and volute (impeller cover). If the magnet is scored, swollen or the shaft broken, there's your problem. Check the volute - if the little hub where the rubber bushing seats the impeller shaft is cracked, there's your problem. Usually the volute cracks first, if it is allowed to run that way, the impeller will "play" and in extreme cases, it can wear the impeller housing within the pump body, to distort, in which case the pump is toast.
If it's just the impeller and/or volute, those can be obtained at much less cost than a replacement pump.
They are so easy to fix, even I can fix them (and that's saying something...)
Jenn