Abstract: A pump and a stress and fatigue resistant pump head, one embodiment of which is useful for a high pressure pump and having a manifold, a valve cartridge, inlet and outlet valves in the valve cartridge, a pump fluid cylinder with a reciprocating plunger therein, a packing cartridge with packing for the plunger. The pump head may exhibit one or more of the following features: a. increased diameter packing cartridge; b. increased length front bushing; c. inclined inlet valve; d. inlet valve spring in valve cartridge on manifold side of valve; e. decreased diameter of high pressure seal of packing cartridge.