Why does he think it needs replacing? Are the rads heating as they should be? Is the boiler displaying any fault codes to do with circulation?
Usual issue is a flat capacitor in the pump that becomes discharged when not in use for long periods such as summer, however, usually fix is to open the pump vent screw & spin the impeller. Once it goes, it will charge the capacitor, which can also be changed cheaply.
Either way, your boiler may have a 5 year warranty and the pump would be covered if so.