A font can be embedded only if it contains a setting by the font vendor that permits it to be embedded.
You may go through the document where it explained in detail-PDF fonts, Adobe Acrobat
The PDF file that you are trying to convert word is that an actual pdf file created using the Acrobat or was created as pdf using some other software?
You can check this under the "Document Properties", Right click on the file>Document Properties>Description.
You may also see- Text is garbled in converted file | ExportPDF