The Biblical verse concerning the body of Moses and the devil you have questions about is located at verse 9 of Jude 1 (Jude only has one chapter).
But Michael the archangel, when he was personally taking issue with the devil, disputing about the body of Moses, did not presume to pronounce a reviling judgment against him . . . (Jude 1:9).
There exists a variety of interpretations in Biblical commentaries regarding this event. Many of them seem, on the surface, to be correct. On closer inspection, however, they are found to be false. For example, one commentary assumes God needed his corpse in order to resurrect him sometime before he appeared in the Transfiguration of Jesus.
In the transfiguration explanation, the devil argues that the physical remains should be left in the ground in an effort to thwart, somehow, God's plans. This argument is groundless since no one has yet to be resurrected from the dead or gone to heaven to receive their reward.
Why Want Moses' Body?
The true Biblical explanation is as follows. The first of the Ten Commandments states that we are to have no other gods before the true God (Exodus 20:1 - 3). The second commandment states that we are not to worship anything God created (verses 4 to 5). Satan the devil, always looking for ways to deceive humans, wanted to make Moses and his grave an object of worship. He wanted Israel to commit idolatry with a dead body!
Israel had formally been guilty of worshipping the golden calf (see Exodus 20 and 32). The body and tomb of Moses, the revered leader of the nation, would have almost certainly would have been a "must see" place to visit by the people of Israel. It could have easily been used by the devil to lead people away from the true God!
Revering the Dead
Strange as it may seem, the practice of revering an important person's corpse does indeed occur today! Those in Russia have access to viewing the embalmed corpses of Stalin or Lenin. Many countries like the United States have a tomb for the "unknown soldier" where people go and dwell on the past.
Memorials force us to dwell in the past, rather than dwelling in the present and going on with our lives. Some people worship these types of memorials as icons. God wants our worship to be only of Him, instead of some shrine to remind us of the past. Satan the devil will use anything he can, even the body of Moses, to try and direct the focus of human minds away from God and onto something that is physical and temporary.