What kind of wound occurs the skin scrapes against a hard surface and tiny blood vessels break in the outer layer of the skin

that kind of wound is called abrasion

Abrasion

Explanation:

An abrasion is a superficial wound requiring only minor first aid.  It occurs when a hard surface has scraped away the first layer of the skin, resulting in minor bleeding at the would site.  Care should be taken to wash the wound with soap and water and to keep the wound clean.