Embedding like this will only lead to pain long term. It's preferable to implement the interface you want to fulfil directly (by having actual method definitions), despite the extra ceremony. Inheritance with embedding is a false friend in Go. Stick to composition.

If you want to delegate a call to a "subtype", simply invoke the method on the subtype by writing it out in long form. It doesn't make you feel as intelligent but it's way more robust and won't come back to bite you down the line.