Warning: Catholic Answer in which I reinterpret what you say about "Word of God" as "things asserted by the Holy Spirit", I think these are equivalent but you may not. This disclaimer might actually be the whole answer to the question, but read on if you dare.
One of awesome and useful documents from 2nd Vatican Council stated:
Therefore, since everything asserted by the inspired authors or sacred writers must be held to be asserted by the Holy Spirit, it follows that the books of Scripture must be acknowledged as teaching solidly, faithfully and without error that truth which God wanted put into sacred writings for the sake of salvation. Therefore "all Scripture is divinely inspired and has its use for teaching the truth and refuting error, for reformation of manners and discipline in right living, so that the man who belongs to God may be efficient and equipped for good work of every kind"
Dei Verbum Ch 3. Paragraph 11
I bolded the word asserted because that's a really, terribly important point. It's not every participle that is the truth that men live on when bread is found to be insufficient. It's the things that the Holy Spirit is trying to tell us through scripture that are the inspired parts. Like, when people to Jesus or Job and told them that a man or his parents must have done something wrong to put him in the place he is. That's not "asserted" by the Holy Spirit in any way.
Furthermore, the Holy Spirit also is the Interpreter of the Sacred Scripture
Read the Scripture within "the living Tradition of the whole Church". According to a saying of the Fathers, Sacred Scripture is written principally in the Church's heart rather than in documents and records, for the Church carries in her Tradition the living memorial of God's Word, and it is the Holy Spirit who gives her the spiritual interpretation of the Scripture (". . . according to the spiritual meaning which the Spirit grants to the Church").
It might be fair to call "the Word of God" as subset of Sacred Scripture because only the good stuff is what is "asserted". But it also might be fair to call Sacred Scripture a subset of the Word of God. Because the good stuff contained in scripture is infinitely deep; It's like Chesterton's porch with an unbelievably gigantic living room or Lewis's tiny gate that keeps on taking you further up and further in.