Brother, in order for this argument to make a logical contradiction. You have to ensure that "word" in those verses means "scripture". It doesn't. No one can change God's word--God's promise, God's plan, God's decisions etc. NOT Allah's scriptures/books. If this verse meant Allah's scriptures, then there would be a contradiction regardless of abrogation because God's words were changed in the bible/torah!
it would be beneficial if the following points be established by the writer, as only the establishment of these points shall be a sufficient argument against the points established in this article:
1.) The words 'Kalimah' and/or 'Kalimaat' [in the Arabic language] are used only for the scriptures revealed by God; or that the Qur'an has, generally, used the words 'Kalimah' and/or 'Kalimaat' for scriptures revealed by God (specifying the verse and giving linguistic and contextual arguments to establish this contention); and
2.) The words 'Kalimah' and/or 'Kalimaat' in the cited verses (in the light of the context of these verses) imply the scriptures revealed by God.
May the Almighty guide us all to the path of His liking.
http://www.understanding-islam.com/articles/miscellaneous-issues/do-the-errors-in-the-bible-prove-that-the-qur-an-is-not-from-god-7Quran 2:106
We do not abrogate a verse or cause it to be forgotten except that We bring forth [one] better than it or similar to it. Do you not know that Allah is over all things competent?