Recipient of Word with embedded PDF can't open PDF object
The embeded object is bundled by COM, the Word program itself will remember the default program for opening embeded PDF document when user embed the PDF into word file. So if the pdf file is embeded as Acrobat object, it can not be opened with Nuance and vice versa, the pdf file embeded as Nuance object can not be opened with Adobe Reader either.
In this case, you insert the PDF document to Word when Nuance is your default, so Word will remembers to use only Nuance to open the document. The recipient doesn't have Nuance, so the error occurs.
If you insert the PDF into Word using Insert>Object >Package, it does not tag the PDF to force open into the embedding program. In other words, it doesn't care if inserted while the PC had Acrobat or Nuance, and doesn't care if the reader trying to access it has Nuance or Acrobat. It opens in any PDF program.