If you mean a human body after they are buried, flies can't get to them. Any eggs laid on them before they are buried may hatch but won't be able to grow on the tissue as the formaldehyde in the enbalming fluid is toxic. Bodies (human and others) buried without enbalming or a coffin may well be partly consumed by maggots laid on them as descibed above, but the number is limited. After feeding their fill for a week they crawl away to pupate and emerge a flies. These flies can not get beack to the buried carcase to re-start another cycle. More likely that worms, beetles and fungi eventually consume the body, leaving the bones and teeth.
Now, aren't you glad you asked? lol