Gear pump having members with different hardnesses

An improved gear pump, comprising:

• a housing having first and second ends and defining an internal bore, an inlet passageway, and an outlet passageway;
• a drive member within the internal bore including a rotor having rotor teeth and a drive shaft extending from the rotor toward the first end of the housing;
• a head member at the second end of the housing including a wall between the inlet passageway and the outlet passageway and extending toward the rotor;
• an idler gear located within the internal bore having gear teeth interengaging with the rotor teeth to pump fluid from the inlet passageway to the outlet passageway;
• mounting means for rotationally mounting the idler gear to the head member;
• the head member and idler gear having a preselected hardness greater than that of the rotor.