A cavitation device is supplied by a disc pump with fluids for mixing. A cavitation rotor, having an array of cavities on its cylindrical surface, is fixed to a shaft for rotation by a motor. The disc pump and the cavitation device are beneficially in the same housing. At least one disc is spaced from and attached to the rotor near the inlet end of the cylindrical housing, so it will rotate with the rotor. A central hole in the (at least one) disc permits fluid to enter the space between the disc and the rotor; it is flung toward the peripheral space between the rotor and the cylindrical housing, where it is subjected to cavitation, and then passed to an outlet. The shaft may pass through one or both of the end walls of the cylindrical housing. The cavitation pump is especially useful for mixing oil field fluids.