There should be a check valve on the discharge pipe.
Replace the check valve (good insurance for the price ~$8).
Remove the pump & pipe from the crock.
Clean out the bottom of the crock.
Inspect the bottom.
You may elect to make it a bit deeper but, keep in mind you may have to add to the length of the discharge pipe.
If the crock bottom won't come clean, you can either lay a thin patio block in the bottom to set the new pump on, or mix up some hydraulic cement and pour a clean bottom.
If you really want to get industrious, you could remove the old metal casing and install a newer pvc casing & lid.
Unscrew the remaining pvc pipe from the old pump.
Apply Teflon tape to the threads of the old pump pipe.
Screw it into the new pump outlet (it appears you won't need any reducers included with the new pump).
Install the new check valve.
Plug the new pump into the outlet.