There isn't very much Aramaic in the bible (parts of the book of Daniel and a smattering of verses in a few other books), I think you mean Hebrew. And no letter

There isn't very much Aramaic in the bible (parts of the book of Daniel and a smattering of verses in a few other books), I think you mean Hebrew. And no letters are inserted. You are thinking of the vowels, but the vowels are not letters, they are represented by a point system. And the Hebrew Bible if fully pointed. It is just modern Hebrew for adult readers that is not pointed (things like the newspaper and novels).