For my pump, if the shaft is deeply scored you need to replace it. If not, you can rebuild it. A rebuild kit is about $80. A new pump $450. If yours is like mine I would take it apart and look at the shaft. If it looks good I would order a rebuild kit. If not I would buy a new pump.
You might get a better answer if you list the model of pump you have. People with the same pump might have better advice.