One embodiment of the invention relates to a liner for a first pump housing in a fluid pump assembly. The fluid pump assembly includes a first pump housing, a second pump housing and a flexible diaphragm disposed between the first and second pump housings. The first pump housing includes a fluid access port for providing fluid communication between an inside housing chamber of the first pump housing and an outside of the first pump housing. The second pump housing is securely mated to the first pump housing. The second pump housing includes a biasing mechanism for selectively displacing a portion of the diaphragm toward the first pump housing. The liner of the invention includes a flexible member removeably secured inside the first pump housing. The liner also includes a first portion of the member being shaped to substantially conform to the interior dimensions of the inside housing chamber and a second portion of the member shaped to substantially conform to the fluid access port. The member forms an inner liner chamber inside the inside housing chamber. The member also includes a mating portion for securing the member to the diaphragm to form a seal there between. The inner liner chamber being in fluid communication with the displaceable portion of the diaphragm. Whereby the displacement of the portion of the diaphragm expels fluid from the inner liner chamber through the fluid access port.