While you could be correct that the pump has excessive wear, which would cause it to act this way, there could also be a problem with the deep well ejector. The ejector has a nozzle in it that has an opening of about 3/16" and could be plugged up. When this happens, the pump cannot build pressure.
After 10 years it might be worth inspecting the pump and replacing/repairing the deep well ejector. Might even want to look at installing a submersible pump.