We say 친구 not 동무. Usually, 동무 is used by North Koreans. Except that, your sentence sounds natural because you said 제 instead of 저의. I think repeating the same word, 의, will make your sentence strange.
저것은 제 친구의 책입니다. This sounds 100 percent natural.
저것은 저의 친구의 책입니다. This sounds a bit awkward to me.