Cavitation pits and erosion were obtained using the rotating disk device, where a steel disk with cavitation inducers and specimens fixed on it rotates inside a water chamber to provide the cavitating flow. These pits were observed with the aid of a scanning electronic microscopy. Micro-jets impingement resulting from bubble ( or cavity) collapse cause damages to solid surfaces on the proximity. Because they are caused by the micro-jets, these pits are spherical. Finally, the pit counting, that is, the number of pits by area and by time unit was calculated. The influence of the flow velocity was also studied here, and how greater is the flow velocity, how greater is the pit counting calculated. It is also studied here other remaining effects (such as “craters”) left during the bubble collapse, High values of temperature (3,000 K) calculated can explain the craters from bubble impactions and the dark spots around them.