Piston pump having plastic material inlet valve insert part for a high pressure cleaning device

A piston pump for a high pressure cleaning device for conveying a cleaning liquid, having a pump housing, which comprises a first housing part and a second housing part that are each configured as a metal part, wherein the first housing part forms a suction conduit and a pressure conduit, and wherein the second housing part forms a plurality of pump chambers into each of which a reciprocally movable piston dips and which are each in flow connection with the suction conduit by way of an inlet channel and with the pressure conduit by way of an outlet channel, wherein the inlet channel can be closed by an inlet valve and the outlet channel can be closed by an outlet valve, wherein the inlet valve comprises a first insert part inserted into the inlet channel and an inlet closing body that is reciprocally displaceable relative to the first insert part, wherein the first insert part comprises an inlet valve seat and a guide member arranged offset from the inlet valve seat, and wherein the inlet closing body comprises an inlet valve plate that can sealingly abut against the inlet valve seat and an inlet valve stem that adjoins the inlet valve plate and is displaceably mounted on the guide member, wherein the first insert part consists of a plastic material and comprises an annular inlet valve seat body, the annular inlet valve seat body pointing toward at least one of the pump chambers and forming the inlet valve seat, wherein the guide member is arranged upstream of the inlet valve seat relative to the flow direction of the cleaning liquid.