Pump, comprising a casing that is generally cup-shaped intended to be fixed to a driving motor (3), and containing a drive shaft (6) suitable for being coupled with said motor, and having a tilted surface for the actuation of one or more pistons (7) that move parallel to the axis of said drive shaft, where said casing consists of a monolithic body (2) that comprises means (4) for its attachment to said motor, a system for supporting and holding said drive shaft, and the guide and sliding seats of the quoted pistons.