In terms of PDF created from Word documents that have EPS files, quite a bit depends upon how you create the PDF file.
Assuming you are on Windows, the only way of creating a PDF file that preserves the full fidelity of the EPS content is to create the PDF by printing to the Adobe PDF PostScript printer driver instance. All other methods (such as the Save as PDF - Microsoft's PDF producer and Save as Adobe PDF - Adobe's PDFMaker) can only use the TIFF preview header of the EPS file, not the PostScript content itself.
In general, you should consider use of EPS in any Microsoft Office application as a legacy, dead-end format that Microsoft is not seriously supporting anymore.
- Dov