pump locking up not a good thing
first i would pull the filter and cut it open and check for metal, also take the locked up pump apart and see how bad the impeller(s) are, if it is bad you probably have alot of metal in the system too.
if you find any you will be having to flush out lines etc to remove any residual metal in the system.
If you do not do this you will be damaging the new pump when it pulls loose metal into it.
It's a big job to do but is necessary when a pump goes out.