The water pump’s main components are:
Gasket: it provides a watertight seal between the pump body and the connection surface on the engine block or the relative cover.
Pulley/Flange: they transmit the motive power to the bearing.
Body: it supports all the other components of the pump and conveys the liquid.
Bearing: it transmits the motive power to the impeller and reacts to the loads generated by the engine.
Mechanical seal: it ensures the pump’s watertightness at all operating speeds, thus preventing the fluid from reaching the bearing and damaging the pump beyond repair.
Impeller: it provides the coolant fluid with the energy it requires to pass through the cooling circuit and thus keep the engine temperature down.