Is it a two line or single line pump? IOWs, is there one line from the well or two? If two, did you change the j-body in the well or check it fro blackage which is more likely. Blockage could have happened when you took the old pump off the plumbing. Or, there is blockage in the jet in the wet end of the new pump from something used in the plumbing of the new pump, or you have a bad new pump.
Quality Water Associates