"This comes through hard work."
Translation:זה בא על ידי עבודה קשָה.
I think דרך os an adverb here and means "by the means of" . It is interesting that על ידי is used here, because it shows a particular relationship when the two objects in the sentence change which one of them affect which one, without loosing central concept of what was said. Example: מיכאל כותב אגדה Michael writes the folk story. האגדה ניכתבת על ידי מיכאל The folk story is being written by Michael. While in both cases Michael is the cause and the folk story is an effect of his actions, second example is more literature way to say something and is a higher Hebrew you will probably not hear on the streets. Definitelly above the level of what have been studied so far.
Saying בדרך isn't grammatically correct here. בדרך means "in a way", "in the way (meaning method), "on the way", "on the road", etc. דרך in this case means "through", for example: היא מבינה דרך מוסיקה - "she understands through music". If I wanted to use בדרך in this sentence, it would be היא מבינה בדרך מוסיקלית - "she understands in a musical way". In the selfsame way, if we wanted to use בדרך in the sentence above, we would eliminate the word עבודה, and leave only the adjective - זה בה בדרך קשה. This would give us a different meaning altogether - "this comes in a difficult way".
If you use זאת you also need to make the verb feminine - באה. But, from what I understand, generally, masculine זה is used for general statements such as this.
Also מעבודה means "from work" or "of work" (for example אני לא מפחד מעבודה קשה - I am not afraid of hard work) which is not what the sentence says, therefore it's not correct. It says "through work" which in Hebrew is דרך עבודה or in this context I think בעזרת עבודה might also work, but I haven't tried it so I don't know if it's accepted.