Scanned images enclosed in PDF files do not have a text layer. When converting such documents to Word, the resulted file will consist of images only.
OCR (optical character recognition) function helps scanned files (any image files) to have the text extracted.
If you need OCR function on daily basis, the best is to own it. The latest Expert PDF provides OCR function for dozen of languages in the Ultimate edition. With Expert PDF Ultimate you can create editable text. If you own another edition of Expert PDF, order a license for the OCR module only or the entire Ultimate package within the software through the Modules and Packages tab.