how to create a PDF with several pages of images, and titles keeping their quality?
Solution 1:
In the Word export dialogue, use the options to tailor the export quality. Particularly, Optimize for image quality.
To get there, choose File > Export
And then on the Publish as PDF dialog click Options
You might also like to try toggling Bitmap text when fonts may not be embedded, as this can sometimes rasterize the text making it look poor in quality.